Method of carbonizing iron and steel



CTI

y UNITED STATES,

PATENT OFFICE.

JEAN HUBERT LOUIS DE BATS, F ZELIEOLPLE, PENNSYLVANI, .ASSIGNR T0 'NEW i IEROCESS METALS CORPORATION,

DELAWARE.

0F WILMINGTON, BELAWARE, A CORPORATION O'F METHOD 0F CARBONIZING IRN AND STEEL.

Specification of Letters Patent. Patented lVIl. 30, 1920.

Applicationl filed .August 19, ISIS. Serial No. 256.462.

To all wlw/m t 'may' concern:

Be it known that I, JEAN HUBERT LOUIS Dn BATS, a resident of Zelienople, in the county of Butler `and State of Pennsylvania., have invented a new and useful Im- `provement in Methods of Carbonizing Iron and Steel, of which the following is a specication.

This invention relates to a method oi' carbonizing iron and steel articles, and its object is to provide a method which Will produce a substantially uniform carboniza-tion of the article throughout its entire cross sectional arca, and whereby the degree of carbonization can be controlled so as to produce substantially equal carbonization of a number of iron or steel pieces, thereby adapting the process to 'the production of toolsteel stock and similar uses.

Accordingto the usual methods of carbonizing iron and steel articles, said articles arc. packed in charcoal or other carbonizing material in a closed container which container Vis placed in a suitable heating furnace Where its temperature is raised and this causes the carbon gases from the carhonizing material to penetrate and deposit carbon in the metal articles. With these old methods the penetration of the carbon into the article is limited. so that only a surface hardening .is secured` or in case the carbonizing` heat is continued so as to penetrate to` or toward the center ot the article, the

an'lount ot carbon in andnear the outer sur-y face of the article is much `greater than that at or toward `the center, and tends to become graphltic. Furthermore, 'when carbonizlng small articles or pieces, a number are packed in the carbonizingl` material in the container, so that those nearest the exterior receive the greatestl degree ot heat and are carhonized `to a greater degree than those near the center of the container.

lilith my method the above objections are overome. ln carrying out the method the articles or pieces to be carbonizcd, such for instance, as low carbon or soft steel, are preliminarily heated iu any suitable way or in any suitable furnace to a point Where the metal begins to become porous. Generally this condition is reached at a temperature of approximately 1100o centigradc. The

pre-heating must be at a slow heat and conv defer a sufficient length of time to insui''the metal becoming porous throughout the cross" section of the article or piece. The pref-heated articles are then allowed to cool, either wholly `or at least to below the point Where they can ignite the carbonizing inatel rial, and are packed in suitable carbonizing material, pre ferablly graphite, and pre 'lierably what is known as graphite lioat," that is. graphite in a very fine condition, and then subjected to the carbonizine; proces@ either in the usual way as' heretoiore practised, but preferably in rotary drum,r to which heat is applied and which is rotated during this part of the process so as to subject all ot'the articles or pieces in the drum to substantially the same temperature and receivethe same degrec of carbon penetration. A suitable apparatus orthis purpose is shown in the ac"- companying dra-Wings, in which Figure l is a longitudinal section through the apparatus; and Figs. 2 and 8 are transverse sections showing respectirel;v the condition in the drum when the latter is stationary and' when it is rotating.

I This apparatus comprises a drum l hav .ing headsclosing its ends and being provided with a refractory lining 3, such as rotated either by frictional contact of the rolls 6' with the bands-5, or, if desired, one or more et' said rolls and bauds may be toothed so as to secure a more positive drive. The drum is provided with an interior lengitudinal heating flue or flues, preferably with a central Hue as shown at 9. Une end of this iue is suitably connected to a source ot heat, such as a gas burner l0, projecting its flame into said fine, and its opposite end is connected by any suitable` rotatable joint to a stack or chimney 11. They construction of this claimed in my application of even date herewith, Serial No. 250,463. The articles to'be treated, shEWn at 12 (in this case tool steel stock o bars) together with the carbonizintif niaterial are placed in the drum, through a suitable door or doors indicated at 14, in one o t' the headsl drum is specifically described and is c 141g. 2, .so that during ofthe drum. The annular space in the drum is only partially filled with such arti- 'cles and carbonizing material, as shown 1n ously and the articles move around therein,

all of the articles or pleces are subjected to the same degree of heat, and the same degree of carbonization is effected. The tem'- pe 'ature applied to the drum is substantially that used in all carbonizing processes, from 800 to S50 degrees centigrade.

By first pre-heating the articles above the critical point, as heretofore pointed out, the molecules are opened' so that when the. articles are subjected te the action of the carbonizing material, which preferably will be graphite "doatf the carbon gases penetrate into the, article or piece, entirely to its center, and to substantially a uniform degree throughout the cross ,section of the article or piece.

-lt has been demonstrated that with this method steel, rods, bars or wires, such as used in the manufacture of nails, bolts,

fstock in a much cheaper sii-ed amount of carbon,

or' the like, can be carbonized to possess an exceedingly fine, silky structure throughout and vsuch that the material is admirably adapted for cold ehisels and other tools, thereby enabling the production of tool steel and more expedit-ious manner than under prior practices. Heretofore it has not been found feasible 4by carbonizing processes to produce teo'l steel stock, due to the fact that the penetration of the carbon is substantially only a surface one. Heretofore tool'steels have been made .by melting in' an open hearth, Crucible, or

electric furnace, a mixture containing the de- I pouring this to form an ingot, and afterward rolling, or 'forging down the ingot into the tool stock. On account of the hardness of the steel the rolling and forging is difficult, and such steel-S are, therefore, quite expensive. lV ith, my method such tool steel can be produced much cheaper, by rolling, forging, or drawingv down the soft steel to they desired cross section or shape, then pre-heating and carbonizing as above described, and insuring tool steel ofuniform haidness and carbon content throughont and of a quality equal, if not superior, to the best quality of carbon tool steel xmunlfactured acct'n'dingf @to the old processes. 1

That I claim is: l. The herein described method of carbonizing iron and steel pieces consisting in prelimimnil)Y heating the pieces to a temperature et approximately 11000 centigrade, thereby .causing tle metal to become porous, cooling the same, and then subjecting the same to a carbonizing temperature while packed in carbonizing material.

QqThe herein described method of carbonizing iron andvsteel pieces, consisting in preliminarily heating the pieces to a' temperature of approximately thereby causing the pores to open up, coolin;v the same, then subjecting the same, when associated with a carbonizing material, and when moving, to a carbonizing temperature.

5. The herein described method of calbonizing iron and steel pieces, consisting in preliminarilyheating the pieces to a temperature of approximately i100O centigrade, thereby causingthe pores to open'up, cooling the same, then packing in float graphite, then agitating, and simultaneously subjecting same to a carlumiziugtemperature. ln testimony whereof, l have hereunto set my hand.

JEAN ltt'lllllt'i LOUIS DE BATS.

lVitness Timm.

11000 centigrade, 

